Like boiled eggs, beans on toast or digestive biscuits, the bacon, lettuce and tomato sandwich is such an everyday item it is easy to forget that it exists. While “bubble-wraps” and broccoli coffee hog the headlines, the BLT occupies a stolid middle-ground of mass consumption, widely eaten but rarely given much thought. The BLT just is. Yet the subject of this month’s How to Eat suddenly finds itself in the news.

First, the Brexit secretary, Dominic “adequate food” Raab, sought to reassure the public that, post-Brexit, there would be no disruption to food supplies. Britain would still be able to make its beloved BLT, he told reporters (#sunlituplands). It was a curious sandwich for Raab to stake his reputation on, given that the BLT originates in the US (was this a coded come-on to Trump for a trade deal?). And that a man from Danepak then predictably came out to say that, actually, no one could guarantee anything after Brexit, and, in the event of no deal, bacon prices would be likely to shoot up.

Raab then had to suffer a second humiliation when a new poll for Warburton’s suggested that, rather than the BLT being a national go-to, it is now a fading 90s’ relic. Despite coming fifth in a survey of Britain’s favourite sandwiches for rival Bird’s Eye as recently as 2016, it was recently reported that the BLT has been usurped by “cosmopolitan” fillings such as brie and cranberry, and “über trendy pulled pork”.

This will be news to anyone who considers pulled pork a bit 2015, and brie and cranberry to be the filling of 1995. But the nation has spoken. If the BLT is on the slide (once, it was also Tony Blair’s focus-grouped, carefully triangulated sandwich of choice), perhaps it just needs a little tender loving dictatorial re-examination of how it should be rendered in its most perfect form.

BL-OTT

In defining what the BLT is, it is important to also stipulate what it is not. It is not a potential party canape. There is no need to reinterpret it as a taco. Every time someone writes a recipe for a bread-free BLT salad, a 200-year-old starter culture dies.

If you want to experiment by adding new flavours to a BLT, a vehicle for that already exists. It is called the club sandwich, which, in its cavalier, anything-goes, let-it-all-hang-out second layer, allows you to add chicken, avocado, cheese, pesto, a fried egg or any of the other numerous unsuitable extra ingredients that, through sheer boredom, people suggest adding to this already perfect sandwich. If you need hot sauce on a BLT then, quite simply, you need to stop smoking.

The BLT should always have hot ingredients, but can three slices of toast be acceptable? Photograph: Alamy Stock Photo

Hot or cold?

Hot. The butter, mayonnaise, tomatoes and lettuce should all be taken from the fridge way in advance. Not just to ensure that they deliver peak flavour (note: in the fridge, the volatile compounds that give tomatoes their pizazz enter a kind of cryogenically suspended inertia), but so that, as they are sandwiched together betwixt hot bacon and golden toast, all the ingredients rapidly achieve a cohesive warmth. A number of now readily melting fats, from the mayo, bacon and butter, should bind the sandwich together as a near-fluid emollient. Is your BLT dripping down your wrists? That is a good thing.

For this reason, and many others, the supermarket chiller BLT is an abomination: as cold and lifeless as the automated factory production line it emerged from. In life, no one wants cold bacon.

Low fat, zero pleasure

Apparently, sandwich manufacturers know that, in the third week of January, after a period of dieting and self-denial, BLT sales spike. That tells you a lot about the essential appeal of this sandwich. It is a treat. An indulgence. One that, even in the onomatopoeia of its acronym, BLT, implies something unapologetically meaty. Any attempt to “lighten” the BLT – swapping butter for avocado, low-fat mayo, turkey bacon etc – erodes that, irrevocably. If you want low-calorie, you are looking at the wrong sandwich.

Composition

Beyond the anticipation-sharpening crisp, audio-sensory crunch of the toasted bread (nb: not toast, but lightly toasted bread), the BLT should deliver several distinct but complementary layers, in which the bacon leads. Ingredient ratios are key. For instance, too much bread will muffle the bacon, to which the tomato, lettuce and mayonnaise should offer accents and inflections, rather than directly competing flavours. Think of this, foremost, as a mediated bacon sandwich.

The BLT should assert its savoury cured pork character in a way that lingers, as the sweet acidity of the tomatoes, the fresh, lightly vegetal bitterness of the lettuce and the creamy tang of the mayo, play at its edges. The whole thing should meld into a mouthful that – simultaneously umami, acidic, sweet, salty, meaty and clean – does a lot of apparently contradictory things at once in such a way that they aremutually reinforcing.

Bread White sliced or, at most, a very lightly malted bread (nothing darker or more worthy), of the best quality you can find or afford. A long-proved, traditional white loaf, soft and strong, is ideal; but a decent supermarket sliced-white bread will work fine. Key points: slices should be no more than 1.5cm thick, and do not go down any speciality baguette/sourdough boule/rye cul-de-sacs. You need a square, plain bread, with a relatively light but durable texture, and one that is not full of holes through which juices will too readily drip.

Bacon Most BLT recipes suggest smoked which, if the bacon is of low-quality, is wise – to inject some flavour (albeit often bullish and inelegant). But if you can source some dry-cured Gloucester Old Spot rashers or similar, let that pure porcine flavour shine.

The supposed gastronomic schism between those who prefer streaky (cooked to a shattering rigidity) and back bacon in their BLT is a whipped-up media controversy. There is a simple solution to this apparent dilemma: use both. Use two or three layers of bacon (depending on its thickness), in which back bacon, its large collar of fat almost melting away, and hard-bronzed streaky, its fat as crispy as bacon Frazzles, are interleaved to offer a variety of bacon sensations. Under no circumstances slice or crumble the bacon. Its rashers should be left intact.

Tomato Cut into roundels of no more than 0.5cm thick. You need a fleshier tomato so its juices do not soak the bread (the often tasteless beefsteak is one option, but experiment). Salt the slices to bring out their flavour.

Lettuce Forget flabby, watery iceberg; spritzy baby gem is the way to go. Under no circumstances start adding rocket, soft salad leaves or other unwanted foliage – this is not a salad sandwich.

Mayonnaise Posher, thicker and/or homemade versions can be too rich and assertive. They can create a cloying BLT. Instead, spread a modest amount of relatively restrained Hellmann’s on each piece of bread, over a layer of butter (salted, always salted). Hellmann’s was advertising itself in Life magazine as the “traditional” mayo for a BLT as early as 1958, albeit alongside a recipe that is wrong in almost every detail.

The cut

The convention of cutting sandwiches into triangular halves is prissy presentational nonsense. Aesthetically, chefs like it because those angles can be artfully arranged on the plate, just as sandwich vendors like to present two fat open-ends to the public. But, gastronomically, it makes no sense. It is almost impossible to fill any sandwich to its very edges, and so those pointed tips on each half of the diagonally-cut sandwich are invariably bereft of filling or, at the very least, make it impossible to take a large, satisfying bite as you would from the middle. Sandwiches should always be cut into two rectangular halves to allow easy entry, whichever way you come at them.

Sides

Fries or coleslaw are pleasant accompaniments but ultimately unnecessary. The BLT needs no such props. But do remember that this is supposed to be a borderline grubby, “dirty” treat. Serve it with a great wodge of salad (when do you eat it: first, second, alongside?) and you drain 87% of the joy from this meal. This is not a sandwich to serve with soup, either. Unlike a grilled cheese sandwich, it contains too many unsecured ingredients to ever work as a dipper.

When

Weekend brunch: the BLT is a bit too busy (and salad-y) for breakfast, and, conversely, a little one dimensional at lunch. But, in that weekend bridging zone, where you have the time and inclination to prepare a belter, it is perfect. Simple but not too simple, this super-charged bacon butty delivers a familiar through-line of flavour with just enough complexity to set you thinking appetisingly – like a promising cinema trailer – about the more grownup meals you will eat after midday.

Drink

In its creamy sweetness, richness and bitterness, coffee mirrors at an angle, the flavours of the BLT. They overlap in a deliciously satisfying way. They are natural partners.